For seamless collaboration, the adaption of the robot to the human should be prompt, and thus the human intent or goal must be inferred during the task execution [1]}, [2]}. Human intent is often considered as a continuous variable [3]}, [4]}, however, it can also reflect discrete changes in the task [5]}, e.g., a collection of possible goals. Discrete human state has been considered for virtual fixtures [6]}, Dynamic Movement Primitives (DMPs) [5]}, and impedance control [8]}.
